Wall-board lath



, Jan. 19 1926.

WALL' BOARD LA'IH Filed July s. 1922 ,$545 I la M705? Joseph A 5U r REJS TTORNm Patented Jamie, 192s. y

- UNITED STATES JOSEPH A. nn'r'rnnss, or scorn rnsanmu, CALIFORNIA.

WALL-nom man.

Application med July 3,

To all whom 'it may co'lwern:

Be it known that I, JOSEPH A. BU'rrREss, a citizen of the United States, residing at South Pasadena, in the county of- Los Angeles, State of California, have invented a new and useful Wall-Board Lath, of which the following is a specification.

My invention relates to -the art of applying plastic surfacing materials to the walls of buildings, and relates particularly to they manufacture and use of plasterboard lath as a supporting means` for such surfaces.

In the construction of buildings, especially in those districts favored with equable climate, plaster is extensively used 'as a surface for both internal walls and ceilings and outside walls. For the purpose of supporting the plaster surface wood lath has been employed almost exclusively up until the late years and makes a very eilicient support for plaster if properly seasoned before use, but causing cracking of the plaster due to expanison and contraction if not thoroughly dried and seasoned before application to the wall structure. In plastering over wood lath, the key between the plaster andthe lath is formed by the plaster entering between the spaces allowed between the adjacent laths.` These spaces being of conslderable length require that the plaster be applied to the laths Witha motion ofthe trowel crosswise to the extension of the spaces between the laths, in order to prevent unnecessary waste of laster. lExpanded metal and wire lath has but has been found to rust dueto the penetration of vmoisture through the plaster, and in a comparatively short tlme causes the fall-l ing away of the plaster surface.

In late years the use of plasterboard has been introduced as a support for plastered' surfaces. This plasterboard is commonlymanufactured by enclosing a layer ofplaster between two sheets of heavy pa er, permitting the plaster to dry between t e sheets of paper); thus forming a board which may be conveniently nailed to the wall framing with considerable economy of application over the wood lath owing to the com aratively large sizes in which the plaster card is manufactured. The difficulties encountered in the manufacture of plaster` board are the tendency to warp when being dried or cured;

overcuring of the edges of the board with a resulting crumbling consistency at the edges;

and the length of time required to properly en somewhat employed,.

1922. Serial No. 572,707.

cure the wallboard due to the insulating effect of the sheets of aper between which the plaster is placed). Although several forms of Wallboard have been developed with surfacesintended to enter into bond with the plaster applied thereto, thus furnishing a means for holding the plaster securely thereupon, it is customary, especially for cuter walls, to employ wire net upon the surface of the plaster board to provide a means for holding the plaster in place after 1t has become dry. The advantages in the use of plasterboard reside in the ease with which it may be applied, the flexibility thereof which adapts it to application upon unevenly placed framework, the amplev strength thereof for the purpose to which it 1s applied, and the equal and very small expansion and contractlon.

It is an object of my invention to provide a plasterboard with which plaster will form a perfect bond without the need of additional securing means, thus providing a plasterboard having the advantages of the ordinary plaster board in combination with the bond qualities of lath. I accomplish this object in the provision of holes which extend entirely through the plasterboard, so that the plaster applied thereto may form a button or hook upon the rear surface of the board and thus constitute an effectualk key for holding the plaster to the board.

It .is a further object of my invention to provlde a particular type of openin which forms a substantial' bond between t e plaster and the plasterboard, and which permits the board tobe applied to the framing with either surface outwardly dis osed.

It 1s a further object of t e invention to provlde a plasterboard having great strength, yet being of practical flexibility. It 1s also an object of the invention to provide a means for supporting plaster surfaces, to which the plaster may be applied with a movement ofthe trowelthereover in any. direction.

It is a still further object of the invention to provide a plasterboard which will reqnre less material in its manufacture and t erefore be of lighter weight and ofcorre.- sppndingly smaller cost of manufacture and s ipment. l

It is a further object of the. invention to 'provide a plasterboard which will dry in a much shorter period of tine than is now necessary, which will not buckle during the curing process, and in which the curing will pro ress evenly throughout the entire area of t e board.

It is a still further object of the invention to provide a plasterboard which will expand and contract evenly over its entire area when subjected to variable conditions.

The specific advantages of the invention and further objects thereof will become evident hereinafter.

Referring to the drawings which are for illustrative purposes only z F ig. 1 is a fragmentary section illustrating the utility of my invention.

Fig. 2 is an enlarged section through the preferable form in which the invention may be embodied.

Fig. 3 is a fragmentary face view of the plasterboard lath.

Fig. 4 is an enlarged fragmentary section illustrating the manner in which the plaster expands within the wallboard openings to form a key between the board and the plaster, when the board is moimted upon sheathing or at points where the board is in en gagement with the structural members upon which it is mounted.

Figs. 5 and 6 are fragmentary sections illustrating other forms of the openings which may be employed in the practice of my invention.

Fig. 7 is a fragmentary section showing an alternative form of opening with which the board may be provided.

In building construction it is customary to nail or otherwise suitably secure wallboard upon the building members provided for the support of the plastered surface. In Fig. 1 I show the wallboard 11, embodying the preferred features of my invention, mounted upon studs 12 and ceiling joists 10. This wallboard is comprised of two sheets of paper 13 having a layer of plaster 15 disposed therebetween and having specially formed openings 16 extending entirely therethrough, so that when the plaster surface 18 is applied to the boards 11, laster keys 19 and 20 will be forced throug the openings 16, whereupon they enlarge upon the back of the wallboard, due to their plasticity, and upon -hardening prevent the removal of the plaster from the wallboard without first breaking the keys.

It is the intention to provide a preferred forni of wallboard having the openings tlierein'diverge or enlarge as they progress rearwardly in order that the keys 19 may assume a wedge-shape formation` or doveiail, within the opening so as to securely lock the plaster surface upon the board.

The particular type of opening 16 which I employ consists of two conical surfaces 25 and 2G which converge as they progress inwardly to the point of conjunction 27. It will be perceived that this formation of opening permits the board to be mounted upon the framework with either surface outwardly disposed, owing to the outward di vergence of the walls 25 and 26 from the central point 27 to the surface of the board.

When placed upon the ceilings the keys are formed as shown at 19 and when the board is used upon vertical walls, the keys assume the form shown at 20, either forni of key being substantially as effective as the other. As shown in Fig. 4 the' plaster which enters those openings which are against the building members, as shown at 30 in Fig. 1, or when the wallboard is mounted upon sheathing 31 as is the common practice iu certain localities, the plaster abuts a ainst the surface 32 and ex ands outward y between the rearwardly iverging walls under the pressure of the trowel, as shown at 33, thus forming a lock between the plaster boards 11 and the plaster 18. In dr ing a certain amount of contraction takes p ace in plaster, and if the openings 16 were provided wit-h the conical form indicated by the dotted lines 34 of Fig. 4, but very small area at the point of juncture of the key with the plaster surface, would be provided to resist the contraction stresses. The formation of the o ening 16 rovides a very broad base 17 for a sorbing the contraction stresses and thereby considerably contributes to the strength of the bond between the wallboard and the plaster. It is not necessary that the openings be of the circular form shown in Figs. 1 to 4, as they may be provided in the square or elongated form 35 and 36 indicated in Figs. 5 and 6, without detracting from their effectiveness.

The paper sheets which enclose the plaster core of the ordinary types of plasterboard serve, as hereinbefore stated, as an isolation between the plaster core and the warm air of the drying kilns. It will be perceived that a greater portion of the drying out of the plaster in said wallboard must take place through the edges, and likewise these edges bein openly subjected to the full heat of the rying kiln, are frequently overcured so as to become crumbly, due to the tendency to crowd the drying operation; while the central portions of the board are undercured. The provision of the openings 16 and and their even distribution over the area of the board 11 as shown in Fig. 3 has thel same effect in the curing of the boards as would the division of the board into small areas havinr their edges open to the influence of the drying kiln interior. The walls 38 of each of the openings 1G provide open Contact of the plaster with the heated drying air, and the drying out of the plaster progresses inwardly from each of the holes as indicated by the arrows, 39, thus accomplishing the curing of the board l1 vcrv evenly and in a very short period of time. u

Fiirthermore, the even drying vout of the pension Iand. eentraction strains within the bodyof thewallboard. In case the finished product is subjected to moisture, 'as when plaster is applied, the moisture permeates lthe board evenly and thus buckling due to vuneven expansion"A and contraction is ,pre-

vented.

- Fig. 7 presents another form of openin r 45 by Whlch the key may be `accomplishe between the plasterboard lath and the plaster.Y The groove 96 providesv an enlargement into which plaster may spread when applied, from either side of the board, and which will serve in conjunction with the button formed upon the back of the board in forming the key. VAlthough the lemploystraight walls would said layer of openin forme of two frusto conical co-axialholes' ment Aol? an aperture having perfectly rovide an eiieient bond between the boar and plaster, it is evident that such bond will not have the inherent strength` attained with the re-` ferred form of opening described and i ustrated.

I claim asv my invention:

A plaster. board comprising: a layerof plaster; a sheet of paper on each side'of laster; said board having theret rough, such openings being having their smallest diameter near the cenl" 

